1. Field of the Invention
This invention relates to a device for fastening a support rail on frame legs of a rack of a switchgear cabinet, wherein the frame legs have two fastening sides oriented perpendicularly with respect to each other and each has a row of square fastening perforations. Both ends of the support rail have fastening brackets which have at least one suspension hook and are matched to the cross section of the fastening perforations in the first fastening side of the frame legs spaced apart between the fastening brackets and to the spacing of the fastening perforations of the frame legs. A clamping plate is assigned to each fastening bracket of the support rail and has retaining claws that extend with the fastening perforations in the second fastening sides of the frame legs. The clamping plates have a threaded receiver for a clamping screw, by which they are maintained on the support rail in an elongated hole extending in a linear direction of the support rail and can be clamped together with the support rail.
2. Description of Related Art
A device of this type is known from German Patent Reference DE 197 12 362 C1 and is used to connect the support rail quickly and solidly with the frame legs of the switchgear cabinet rack.
The support rail, which has the suspension hook, can be provisionally suspended in fastening perforations of the frame legs and in mounting plates, so that the assembler has both hands free for further mounting work. The clamping plates, which are held on the support rail by the clamping screws, are also introduced into the fastening perforations of the frame leg, or are moved behind the retaining strip of the mounting plate.
The elongated holes in the support rail permit the adjustment of the clamping plates at the end of the support rail. When the clamping screws are tightened, the support rail and the clamping plates are clamped against each other. The support rail rests on a fastening side of the frame leg and the clamping plates enter with retaining claws into the fastening perforations of the fastening side extending perpendicularly with respect to the fastening side. The base leg of the support rail has fastening bores in the linear direction, which can be used for attaching devices to the support rail. However, the support rail is not optimally suited for fastening bus bars of a bus bar system, and thus is not adapted to the special requirements of a bus bar holder for making their mounting easier.
It is one object of this invention to provide a device of the type mentioned above but with simple means so that the support rail meets the requirements of a bus bar holder and simplifies the mounting of the bus bars of a bus bar system.
In accordance with this invention this object is attained with a device formed as a bus bar holder with a pair of threaded receivers per bus bar, into which retaining bolts with a threaded part, which is reduced in diameter, can be screwed. With the retaining bolts U-shaped insulating receivers can be fixed on the support rail, having a receiver matched to the exterior dimensions of the bus bars. The insulating retaining clip can be closed by a retaining strip, wherein the connecting screws can be screwed into screw receivers on the front face of the retaining bolts.
The pairs of threaded receivers are spaced apart, and the spacing between the pairs is matched to the prescribed arrangement of the bus bars of the bus bar system extending parallel with each other. Connected with the support rail, the insulating retaining clips form open receivers, into which bus bars of corresponding exterior dimension can be inserted. The bus bars are held in the insulating retaining clips with retaining strips which connect the free ends of the lateral legs of the insulating retaining clips, close the receiver and fix the inserted bus bar in place in the receiver.
If the support rail with a base leg and two lateral legs has a U-shaped cross section, and the clamping plates with a base leg and two lateral legs are also U-shaped and form a receiver for the support rail, then the support rail has sufficient stability to support even heavy bus bars. Also, the clamping plates can be easily adjusted in the linear direction on the support rail for bringing into a connecting position with the frame legs.
Connecting the insulating retaining clips with the pairs of threaded receivers of the support rail is easier because the insulating retaining clips have bores, which are stepped in diameter and are matched to the stepped retaining bolts. Bus bar systems for large current strengths often use bus bars with essentially square exterior dimensions. In one embodiment, the receiver of the insulating retaining clips is matched to the square exterior dimensions of the bus bar to be received, wherein a layout matches the pairs of threaded receivers of the support rail to the distance between the parallel bus bars of a multi-phase bus bar system.
The suspension of the support rail on the frame legs is simplified because the retaining claws of the clamping plate are formed on an edge of the clamping plate, extending vertically with respect to the linear direction of the support rail. The fastening sides of the frame legs are oriented transversely with respect to the linear direction of the support rail, wherein the direction for suspending the support rail is dictated by the orientation of the retaining claws and the frame legs.
The support rail and the clamping plates are advantageously embodied and produced as separate punched and bent elements.
In accordance with a further embodiment, the insulating retaining clips are assembled from a base plate and two lateral legs, or are made in one piece. The base plate and the lateral legs are made from an insulating material, for example plastic, in order to insulate the bus bar inserted into the receiver of the insulating retaining clip against the metal support rail.
In case of separate elements, for example a base plate and lateral legs, of the insulating retaining clips, it is advantageous for attaching these elements to the support rail if the base plate has cutouts at the end, which receive and position the lateral legs, and the base plate itself has positioning legs which are at a distance from the lateral legs and delimit a receiver for the lateral legs of the support rail. The retaining strip has laterally protruding positioning strips which form stops for the lateral supports of the insulating retaining clip.
In a further embodiment, the frame legs can be replaced by mounting rails, having a second fastening side designed as a retaining strip. The retaining claws of the clamping plates extend behind this retaining strip because the mounting rails have rows of fastening perforations only in the base leg. With the mounting rails it is possible to create connecting points in the switchgear cabinet, even if the parallel extending frame legs have a greater distance from each other than the fastening brackets of the support rail. The mounting rails can be connected with the frame legs of the rack of the switchgear cabinet.